The　metal-support　interactions　induced　by　high-temperature　hydrogen　reduction　have　a　strong　influence　on　the　catalytic　performance　of　ceria-supported　Ru　catalysts.　However,　the　appearance　of　the　strong　metal-support　interaction　leads　to　covering　of　the　Ru　species　by　Ce　suboxides,　which　is　detrimental　to　the　ammonia　synthesis　reaction　that　requires　metallic　species　as　active　sites.　In　the　present　work,　the　interaction　between　Ru　and　ceria　in　the　Ru/CeO2　catalyst　was　induced　by　NaBH4　treatment.　NaBH4　treatment　enhanced　the　fraction　of　metallic　Ru,　proportion　of　Ce3+,　content　of　exposed　Ru　species,　and　amount　of　surface　oxygen　species.　As　a　result,　a　larger　amount　of　hydrogen　species　would　desorb　by　the　H-2-formation　pathway　and　the　strength　of　hydrogen　adsorption　would　be　weaker,　weakening　the　inhibition　effect　of　the　hydrogen　species　on　ammonia　synthesis.　In　addition,　the　strong　electronic　metal-support　interaction　aids　in　nitrogen　dissociation.　Consequently,　Ru/CeO2　with　NaBH4　treatment　showed　higher　ammonia　synthesis　rates　than　that　with　only　hydrogen　reduction.　(C)　2021　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　ELSEVIER　B.V.　and　Science　Press.　All　rights　reserved.